Figure 1.
Serotonin-induced changes in tCREB1 and CRE-mediated gene expression. A, 5-HT treatment induced tCREB1 expression for at least 24 h in cultured SNs. A1, Representative confocal images of tCREB1 immunofluorescence in SNs at 2, 12, and 24 h after treatment with vehicle or 5-HT. Scale bar, 30 μm. A2, Summary data. CREB1 was elevated at 2 h, returned to basal level at 12 h, and increased again at 18 and 24 h after 5-HT treatment (*p < 0.05). B, CRE-mediated EGFP expression was enhanced 18–24 h after 5-HT treatment. B1, Representative images of sensory cells injected with CRE–EGFP reporter vector 18 h after 5-HT or vehicle treatment and fixed 6 h later. Texas Red–dextran was added to the injection buffer to confirm nuclear injection. Scale bar, 15 μm. B2, 5-HT-induced EGFP expression was calculated as the ratio of the 5-HT-treated to vehicle-treated samples for each experiment. EGFP expression was significantly increased in neurons after 5-HT treatment compared with vehicle-treated cells (*p < 0.05), demonstrating that CRE-dependent gene expression is still enhanced 18 h after 5-HT treatment.